Prognostic Meteorological Discussion
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FXAK02 KWNH 201946
PMDAK

ALASKA EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
345 PM EDT WED SEP 20 2017

VALID 12Z SUN SEP 24 2017 - 12Z THU SEP 28 2017

THERE IS STILL SOME SPREAD CONCERNING THE DEPTH OF THE INTENSE
CIRCULATION THAT SITS OR EXTENDS FROM THE SERN BERING SEA TO THE
NWRN GULF OF AK ON SUN/MON. MUCH LARGER SPREAD EXISTS TUES-THURS,
AS OPERATIONAL GUIDANCE VARY QUITE A BIT WITH HEIGHT FALLS PASSING
THROUGH THE NORTHERN/NERN PORTION OF THE STATE, ALONG WITH ANOTHER
PAC SYSTEM POTENTIALLY LIFTING NORTH AND EAST TOWARD THE GULF OF
AK/NERN PAC. CONCERNING THE MODEL BLEND, A BLEND OF THE 00Z
ECMWF/CANADIAN WITH THE EC AND NAEFS MEANS IS A SOLID START
SUN-MON, AS THIS QUARTET CAPTURES A MUCH DEEPER SOLUTION WITH THE
RELATIVELY STACKED LOW THAN COMPARED TO THE WEAKER VERSIONS OF THE
GFS AND GEFS. THEN ON TUES-THURS, WPC TRANSITIONED TO 70-90
PERCENT OF THE BLEND ALL 00Z MEANS, EC/GEFS/NAEFS. THIS WAS TO
REDUCE NOT ONLY THE SPREAD TO THE NORTH AND SOUTH OF THE STATE BUT
REMOVE THE UNCERTAINTY TO CAPTURE THE LARGE SCALE PATTERN INTO
NEXT WEEK. BY FOLLOWING THE ECMWF MORE THAN THE GFS, THE BIGGEST
SENSIBLE WEATHER ISSUE WILL BE A CONSTANT STREAM OF MOISTURE
IMPACTING THE SOUTHERN PORTION OF THE STATE FROM THE UPPER
ALEUTIANS THROUGH THE SOUTHERN PENINSULA TO THE PANHANDLE, WHERE 5
TO 10 INCH AREAL AVG QPF AMOUNTS WILL BE POSSIBLE.


MUSHER


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